The present invention relates to novel imidazonaphthyridine derivatives having 1H,5H- or 3H,5H-imidazo[4,5-c][1,8]naphthyridin-4-one skeleton and which show an anti-inflammatory activity, an anti-allergic activity and a broncho-dilative activity.
Imidazo[4,5-c]quinoline derivatives having a broncho-dilative and antiviral activity are disclosed in Japanese Published Unexamined Patent Application No. 1234881/85 (U.S. Pat. Nos. 4,698,348 and 4,689,338 and EP-A-145340). However, 1H,5H- or 3H,5H-imidazo[4,5-c][1,8]-naphthyridin-4-one derivatives and their pharmacological activity are unknown.